The biology of endothelial cells (EC) is central to the laboratory's long-term objectives. Specifically, we wish to demonstrate: 1) that EC are a metabolic as well as an anatomic barrier, 2) mechanisms by which specific vasoactive substances breach the barrier, 3) unique characteristics of microvascular EC, and 4) that EC in culture are valuable experimentally because they respond physiologically to specific stimuli as their counterparts do in vivo. Current proposed aims are to demonstrate nonrespiratory metabolic functions of pulmonary EC (PEC) isolated from canine, bovine and human tissues. The projected studies are based upon the premise that PEC dysfuncton, caused by hypoxia or chemical and mechanical pertubation, results in an abnormal outpouring of fatty acid metabolites and a breakdown of serotonin and norepinephrine clearance. The outcome of this PEC pathophysiologic state is that amine and fatty acid autocoids, because of prolonged secretion by PEC, became vasotoxic and contribute importantly to non-hydrostatic pulmonary edema and decreased cardiac output. The circulating proin-flammatory agents exacerbate existing inflammatory conditions and can initiate new injury in other areas of the traumatized lung and in a non-injured contralateral lung. In other words, focal pulmonary microvascular perturbation can lead to distant inflammatory sequellae because of circulating inflammatory mediators. An hypoxic environment is theorized to stimulate the release of PEC fatty acids, which are shunted abnormally into thromboxane synthesis. The in vitro assays are designed to determine the conditions by which PEC, in response to known prophlogistic agents, produce more of these inflammatory substances. Also, how eicosanoids affect PEC PEC Serotonin and norepinephrine clearance, and how these amines affect eicosanoid synthesis will be tested. The cultured PEC will thus be used as both a substrate for secretion and as a target tissue. The mechanism of action and the prevention of vasotoxic agents mediating increased pulmonary permeability and decreased cardiac output will also be tested with animal models and isolated organ assays.